When an email is deleted in Gmail it is automatically sent to the trash. Items in your Trash will remain there for approximately 30 days before it is automatically emptied and permanently deleted.
If you'd like to permanently delete something yourself:
1. Click your Trash label.
2. Check the box next to the message you'd like to permanently delete.
3. Click the Delete forever button.
You can retrieve something from Trash by clicking Trash, selecting the message in question, and clicking Inbox in the 'Move to' drop-down menu. Items that are permanently deleted can't be retrieved.
Please revert for clarification.